/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package club.dawdler.clientplug.web.session.base;

/**
 * @author jackson.song
 * @version V1.0
 * SessionId生成者 直接copy tomcat代码
 */
public class StandardSessionIdGenerator extends SessionIdGeneratorBase {

	@Override
	public String generateSessionId(String route) {

		byte[] random = new byte[16];
		int sessionIdLength = getSessionIdLength();

		// Render the result as a String of hexadecimal digits
		// Start with enough space for sessionIdLength and medium route size
		StringBuilder buffer = new StringBuilder(2 * sessionIdLength + 20);

		int resultLenBytes = 0;

		while (resultLenBytes < sessionIdLength) {
			getRandomBytes(random);
			for (int j = 0; j < random.length && resultLenBytes < sessionIdLength; j++) {
				byte b1 = (byte) ((random[j] & 0xf0) >> 4);
				byte b2 = (byte) (random[j] & 0x0f);
				if (b1 < 10) {
					buffer.append((char) ('0' + b1));
				} else {
					buffer.append((char) ('A' + (b1 - 10)));
				}
				if (b2 < 10) {
					buffer.append((char) ('0' + b2));
				} else {
					buffer.append((char) ('A' + (b2 - 10)));
				}
				resultLenBytes++;
			}
		}

		if (route != null && route.length() > 0) {
			buffer.append('.').append(route);
		} else {
			String jvmRoute = getJvmRoute();
			if (jvmRoute != null && jvmRoute.length() > 0) {
				buffer.append('.').append(jvmRoute);
			}
		}

		return buffer.toString();
	}
}
